You can't change FIOS or cable modem MAC address to get a new IP address.
Those MACs are your ID subscription to connect to ISP server.
The IP you received is assigned to whatever device you have after modem.
If you want a new IP, you have to change MAC on "device" which connects to your modem.
"Device" is a router, network card in a PC or laptop.
Once MAC is changed, you can cycle power to modem within 30s to 1m, you will get a new IP.
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